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  • Last modified 2556 days ago (Sept. 21, 2011)

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Fish clog water intakes

Staff writer

“A fine kettle of fish” is not the way city officials in Marion and Hillsboro described an unusual shad run Monday that resulted in both city water intakes being clogged by thousands of the small silver baitfish.

“We are sucking up thousands of shad,” Marion city administrator Doug Kjellin said Monday.

“We did not have a flow problem until Monday, and we started cleaning the baskets, and that’s when we discovered the shad,” Hillsboro water supervisor Morgan Marler said.

Kjellin said the unusual circumstance occurs every 10 years or so, and is triggered by the rapid change from hot to cool weather. The change has forced the shad deeper in the reservoir than normal, where they are sucked in by the water intake that lies 18 feet beneath the surface of the water.

“This shad problem has happened before – I have heard the previous operators talk about it before,” Marler said.

Marion and Hillsboro water departments coordinated efforts to use what Marler described as “blow-off systems” to initially purge the lines.

“It’s a piping system, a big 12 inch line – it’s just a flush line we can open up and flush the entire line from the pump house to the intake,” Marler said regarding Hillsboro’s system, which was originally intended to battle infestations of zebra mussels.

“We coordinated with the city of Marion and opened up both of the blow-off lines and flushed all of that out of there,” Marler said.

The towns share the water intake, according to Kjellin, and the combined flush forced 4,000 to 5,000 gallons per minute through the pipe to clear any obstructions.

The Marion water intake kept water department employees busy Monday with frequent trips to clear the basket covering the intake.

“About every half hour they clear the line right now,” Kjellin said Monday. “We monitor at the water plant and when the amount of flow drops to some level then we know there’s an obstruction in the strainer basket and somebody goes out and dumps out the basket.”

While the shad are a nuisance, Kjellin emphasized the water supply is not being adversely affected.

“We’re on top of it, and the water supply’s not in danger at all,” Kjellin said. “It’s just a naturally occurring event and we’ll work our way through it.”

Contacted Tuesday afternoon, Kjellin said the shad infestation had vanished.

“The guys went out this morning to open up the strainer basket container and they found one shad,” Kjellin said.

“It must have been some environmental event that caused them to get close to the intake, and we sucked a whole school of shad in,” Kjellin concluded.

According to Marler, Hillsboro’s water intake was not experiencing any additional difficulties Tuesday afternoon.

“We’re not having any flow issues – we have it under control,” Marler said.

“It’s just nature’s way of keeping us on our toes,” she added.

Last modified Sept. 21, 2011

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